An on-site device for detecting presence of a liquid from a site and a method for detecting presence of a liquid from a site using the on-site device, the device comprising a moisture detector arranged to detect the presence of the liquid based on one or more electrical characteristics of the liquid; a first optical detector assembly coupled to the moisture detector, the first optical detector assembly being configured to be activated upon detection of the presence of the liquid by the moisture detector; and wherein upon activation, the first optical detector assembly is configured to detect a substance in the liquid based on one or more optical characteristics of the substance.